The present application relates to an optical element covering member, a backlight including the same, and a liquid crystal display device, and more particularly, relates to an optical element covering member which improves display performance of a liquid crystal display device.
Heretofore, in a liquid crystal display device, many optical elements have been used in order to improve the viewing angle, luminance, and the like. As these optical elements, films and sheets, such as a diffusion film and a prism sheet, have been used.
FIG. 15 shows the structure of a liquid crystal display device of a related art. This liquid crystal display device includes, as shown in FIG. 15, a lighting element 101 emitting light, a diffusion plate 102 diffusing light emitted from the lighting element 101, a plurality of optical elements 103 condensing and/or diffusing light diffused by the diffusion plate 102, and a liquid crystal panel 104.
Incidentally, in recent years, concomitant with an increase in size of a liquid crystal display device, the weight and size of an optical element itself tends to increase. When the weight and size of an optical element itself increases, since the rigidity thereof becomes insufficient, the optical element is liable to be deformed. The deformation of the optical element as described above causes adverse influence on optical directional characteristics to a display surface, and as a result, a serious problem, that is, luminance irregularity, may arise.
Accordingly, an improvement of insufficient rigidity of an optical element by increasing the thickness thereof has been proposed. However, since the thickness of a liquid crystal display device is increased, its advantageous properties, such as small thickness and light weight, are degraded. Hence, it has been proposed that by bonding optical elements to each other with a transparent adhesive, insufficient rigidity of an optical element in the form of a sheet or a film is improved (for example, see Japanese Unexamined Patent Application Publication No. 2005-301147).